Weed cutter

ABSTRACT

A weed cutter that may be pulled behind a tractor is provided. The weed cutter has plurality of cutting blades that rotate when acted upon by planetary gears rotating around a central sun gear. A planetary gearbox assembly with a cloverleaf shape rotates partially around fence posts and other objects to cut weeds growing around the objects.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/162,424 filed on Mar. 23, 2009, the entire contents of which areherein incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to the field of tractor-based,rotary-driven power equipment, and more particularly relates to a weedcutter.

BACKGROUND AND SUMMARY OF THE INVENTION

Traditional weed cutters must be manually guided around corners andobstacles. Using a tractor to cut weeds around objects like fence posts,for example, can therefore be a challenge. However, cutting weeds aroundfence posts with a hand-held weed cutter is quite labor intensive.

A weed cutter of the present disclosure provides a cutting deck with aunique “cloverleaf” shape that rotates around fence posts, cutting weedsfrom around three sides of the fence posts while the cutter moves in asingle direction of travel. In one embodiment, the weed cutter comprisesthree (3) cutting heads that comprise planetary gears rotating aroundthe perimeter of a central sun gear.

In one embodiment, the weed cutter is attached to and is pulled behind atractor that powers the cutter. In this regard, a gearbox on the cutterconnects to the power take-off (PTO) of the tractor, which providesrotation to the cutter's gears, which translates the rotation from thePTO to rotary cutting blades that cut grass and other ground vegetation.

For purposes of summarizing the invention, certain aspects, advantages,and novel features of the invention have been described herein. It is tobe understood that not necessarily all such advantages may be achievedin accordance with any one particular embodiment of the invention. Thus,the invention may be embodied or carried out in a manner that achievesor optimizes one advantage or group of advantages as taught hereinwithout necessarily achieving other advantages as may be taught orsuggested herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be better understood with reference to the followingdrawings. The elements of the drawings are not necessarily to scale,emphasis instead being placed upon clearly illustrating the principlesof the disclosure. Furthermore, like reference numerals designatecorresponding parts throughout the several views.

FIG. 1 is a bottom plan view of an exemplary weed cutter in accordancewith an embodiment of the present disclosure.

FIG. 2 is an end view of the weed cutter of FIG. 1.

FIG. 3 is a functional representation of the gears of the weed cutter ofFIG. 1.

FIG. 4 depicts the gears of an exemplary weed cutter in accordance withan embodiment of the present disclosure.

FIG. 5 depicts an exemplary weed cutter just before the cutter comes incontact with a fence post.

FIG. 6 depicts the weed cutter FIG. 4, after the cutter has contactedthe fence post.

FIG. 7 depicts the cutter of FIG. 4, as the cutter continues to rotatearound the fence post.

FIG. 8 depicts the cutter of FIG. 4, as the fence post contacts theindentation.

FIG. 9 depicts the cutter of FIG. 4, as the cutter continues to rotatearound the fence post.

FIG. 10 is a functional flowchart illustrating an exemplary method ofcutting weeds in accordance with an embodiment of the presentdisclosure.

FIG. 11 is a perspective view of a planetary gearbox assembly accordingto an embodiment of the present disclosure.

FIG. 12 is a top plan view of a planetary gearbox assembly according toan embodiment of the present disclosure

DETAILED DESCRIPTION

FIG. 1 is a bottom plan view of a weed cutter 10 according to anexemplary embodiment of the present disclosure. The weed cutter 10comprises a plurality of cutting heads 12 a-12 c comprising blades 13that extend from the cutting heads 12 a-12 c. Each cutting blade 13 hasat least one sharpened edge (not shown) for cutting weeds (not shown).

Each cutting head 12 a-12 c rotates or spins around an axis 9 a-9 c,respectively, in the direction indicated by directional arrows 16. Therotation of the cutting heads 12 a-12 c defines circular footprints 25a-25 c that are the cutting area of the blades 13 attached to cuttingheads 12 a-12 c. Although the illustrated embodiment depicts three (3)cutting heads 12 a-12 c, more or fewer cutting heads may be employed inother embodiments.

A planetary gearbox assembly 40 is a housing containing gears (notshown) that impart rotation to the cutting heads 12 a-12 c, as furtherdescribed herein. The planetary gearbox assembly 40 comprises a topplate (not shown), a bottom plate 44, and an edge guard 17. The edgeguard 17 is disposed outside of the circular footprints 25 a-25 c thatdefine the cutting area of the blades 13 attached to cutting heads 12a-12 c. Because the edge guard 17 extends outside of the circularfootprints 25 a-25 c, the edge guard 17 protects the blades 13 fromdamage due to side impacts between the gearbox 40 and an obstacle (notshown).

The edge guard 17 comprises a plurality of convex protrusions 33 a-33 ccorresponding to and slightly larger than the circular footprints 25a-25 c, respectively. Note that cutting head 12 a is disposed directlybeneath protrusion 33 a, cutting head 12 b is disposed directly beneathprotrusion 33 b, and cutting head 12 c is disposed directly beneathprotrusion 33 c.

The edge guard 17 further comprises a plurality of indentations 32 a-32c, such that the general shape of the edge guard 17 is similar to athree-leaf clover in the illustrated embodiment. The indentation 32 a isdisposed between convex protrusions 33 a and 33 b; the indentation 32 bis disposed between convex protrusions 33 b and 33 c; the indentation 32c is disposed between convex protrusions 33 c and 33 a.

The planetary gearbox assembly 40 rotates around a central axis 30 inthe direction indicated by directional arrow 42.

In one embodiment, a shaft 14 connects to a tractor (not shown) andtransfers rotation from the tractor to the planetary gearbox assembly40. In this regard, the shaft 14 connects to the power take-off (PTO)(not shown) of the tractor. As is known by persons of skill in the art,a PTO is a splined driveshaft on a tractor or truck that is used toprovide power to an attachment or separate machines. The PTO providesrotation to the shaft 14, which imparts rotation to the planetarygearbox assembly 40, as further discussed herein. The tractor typicallymoves in the direction shown by directional indicator 35. In otherembodiments of the cutter 10, the rotation of the planetary gearboxassembly 40 may be driven by a mower instead of a tractor.

FIG. 2 is an end view of the weed cutter 10 of FIG. 1. A plurality ofsupport arms 46 extend from a top plate 45 of the planetary gearboxassembly 40 and support a shaft sleeve 50, as further discussed withrespect to FIG. 11 herein. The shaft sleeve 50 connects to a lift frame(not shown) which structurally supports the weed cutter 10. In thisembodiment, the cutting heads 12 a-12 c extend below the bottom plate 44of the planetary gearbox assembly 40, but the outside edges 46 of theblades 13 do not extend past the outside edges 47 of the edge guard 17.

FIG. 3 is a functional representation of exemplary gears that operatethe weed cutter 10 according to an embodiment of the present disclosure.A centrally-located rotating sun gear 11 rotates around a central axis30. The sun gear 11 rotatably connects to a plurality of planetary gears8 a-8 b which correspond to cutting heads 12 a-12 c. In this regard, thesun gear 11 comprises a plurality of teeth 24 that interlock with teeth23 on the planetary gears 8 a-8 c.

Each of the planetary gears 8 a-8 c connects to its correspondingcutting head 12 a-12 c via a shaft 48, such that the cutting heads 12a-12 c rotate with the planetary gears 8 a-8 c. When the sun gear 11rotates in the direction indicated by directional arrow 15, theplanetary gears 8 a-8 c and the cutting heads 12 a-12 c rotate in thedirection indicated by directional arrows 16. The cutting heads 12 a-12c rotate at higher speeds than the sun gear 11

The sun gear 11 receives rotation from the shaft 14 via a right anglegearbox 41 which comprises gears 19 and 22 that translate rotation fromthe shaft 14, which is generally vertically oriented, to a verticalshaft 6 rigidly affixed to the sun gear 11. When the shaft 14 rotates inthe direction indicated by directional arrow 18, the sun gear 11 rotatesin the direction indicated by directional arrow 15.

In other embodiments, a different right angle gearbox 41 may be usedthat reverses the rotation of the sun gear 11 from the directionindicated by directional arrow 15.

FIG. 4 depicts the gears 11 and 8 a-8 c of the weed cutter 10 (FIG. 1)according to an embodiment of the present disclosure. In thisembodiment, the sun gear 11 and planetary gears 8 a-8 c are configuredsuch that the sun gear 11 rotates at a speed of about 750 rpm and thecutting heads 8 a-8 c rotate at a speed of about 3000 rpm. Exemplarydimensions that result in these rotation speeds are:

-   -   a. an outer diameter of the sun gear 11 of 20 inches;    -   b. an outer diameter of the planetary gears 8 a-8 c of 5 inches;    -   c. an outer diameter of the circular footprints 25 a-25 c        (defined by the outside edges 46 (FIG. 2) of the cutting blades        13 (FIG. 2) of about 20 inches;    -   d. a distance d_(s) between a center of the sun gear 11 to a        center of the cutting heads 12 a-12 c of 12.550 inches;    -   e. a longitudinal distance d_(l) between a center of the cutting        head 12 a and the cutting head 12 b of 18.825 inches;    -   f. a transverse distance d_(t) between the center of the cutting        head 12 a and the center of the cutting head 12 c of 21.737        inches;    -   g. a distance d_(p) between the outside perimeter of circular        footprints 25 b and 25 c of 1.737 inches.

The rotation speeds and related dimensions are provided for exemplarypurposes only, and other rotation speeds and dimensions may be utilizedin other embodiments.

FIG. 5 is a bottom view of an exemplary cutter 10 in operation, justbefore the protrusion 33 a of the cutter 10 comes in contact with afence post 31. In this embodiment, the cutter 10 is attached to the PTOof a tractor (not shown), which rotates the shaft 14 and causes thecutting heads 12 a-12 c to rotate. The cutter 10 is pulled behind thetractor with the tractor moving in the direction indicated bydirectional arrow 35. Before the protrusion 33 a contacts the fence post31, the planetary gearbox assembly 40 does not rotate, as in thisembodiment the gearbox assembly rotates only when acted on by an outsideforce.

FIG. 6 depicts the cutter 10 of FIG. 5, after the protrusion 33 a hascontacted the fence post 31. The force of the fence post 31 coming incontact with the guard 17 causes the planetary gearbox assembly 40 tobegin to rotate around its central axis 30 in the direction indicated bydirectional arrow 36. This rotation causes the blades 13 of the cuttinghead 12 a to cut undergrowth (not shown) adjacent to a first side 37 ofthe fence post 31. In this regard, although the edge guard 17 preventsthe blades 13 from contacting the fence post 31, the blades 13 extendbeneath the guard 17 and contact the undergrowth beneath the guard 17 tocut the undergrowth.

Note that the rotation of the planetary gearbox assembly 40 when itcontacts the fence post 31 is in the opposite direction from therotation of the cutting heads 12 a-12 c. In this embodiment, therotation of the cutting heads 12 a-12 c is intended to somewhat “resist”the rotation of the assembly 40. In other embodiments, the rotation ofthe cutting heads 12 a-12 c may be in the same direction as the intendedrotation of the assembly 40, in order to assist the forward motion ofthe assembly 40 around the post 31. Therefore, different gearconfigurations than those discussed herein may be employed withoutdeparting from the scope of the present disclosure.

FIG. 7 depicts the cutter 10 of FIG. 5, as the planetary gearboxassembly 40 continues to rotate “around” the fence post 31 in thedirection indicated by directional arrow 36. In this regard, protrusion33 a contacts first side 37 of the fence post 31 and the blades 13 ofcutting head 12 a continue to cut weeds adjacent to the fence post 31.Because the blades 13 do not extend beyond the perimeter of theprotrusion 33 a, the blades 13 do not contact the fence post 31 itself.

FIG. 8 depicts the cutter 10 of FIG. 5, as the fence post 31 contactsthe indentation 32 c. As the planetary gearbox assembly 40 continues torotate around the fence post 31, the fence post contacts protrusion 33a, indentation 32 c, and then protrusion 33 c, and the blades 13 on thecutting heads 12 a and 12 c cut the undergrowth adjacent to a secondside 38 of the fence post 31.

FIG. 9 depicts the cutter 10 of FIG. 5, as the planetary gearboxassembly 40 continues to rotate around the fence post 31 with theprotrusion 33 c contacting a third side 39 of the fence post 31 and theblades 13 on the cutting head 12 c cuts weeds adjacent to the third side39 of the fence post 31. At this point the planetary gear assembly 40has rotated 120 degrees from its initial position (shown in FIG. 5) andthe planetary gear assembly 40 is in position to encounter another fencepost and start the process again.

Note that the orientation of the cutter 10 rotating around the fencepost 31 enables the cutter 10 cut around three sides, namely first side37 (FIG. 5), second side 38 (FIG. 7) and third side 39 (FIG. 9) of thefence post 31 with the tractor still traveling in generally the samedirection, i.e., the direction indicated by directional arrow 35. If theuser (not shown) is cutting weeds along a fence row, the user may drivethe tractor along one side of the fence to cut around three sides ofeach fence post and then may drive the tractor along the other side ofthe fence to cut the remaining weeds from the fourth side of each fencepost. Although the description herein references four sides of a fencepost, the weed cutter 10 may rotate around and thus cut weeds aroundobjects of many different shapes, such as round fence posts. Further,although the description herein refers to fence posts, the weed cutter10 may cut weeds adjacent to many different types of objects.

FIG. 10 depicts a method of cutting weeds according to an embodiment ofthe present disclosure. In step 100 of the method, the planetary gearboxassembly 40 of the weed cutter 10 begins to rotate when its convexportion (33 a, 33 b or 33 b) (FIG. 5) contacts a fence post 31 (FIG. 5).In step 101, the cutting blades 13 (FIG. 5) cut undergrowth adjacent tothe first side 37 of the fence post 31 (FIG. 1) as the planetary gearboxassembly 40 rotates slowly around the fence post 31. In step 102, thecutting blades 13 cut undergrowth adjacent to a second side 38 (FIG. 8)of the fence post 31 as the planetary gearbox assembly 40 continues toslowly rotate around the fence post 31. In step 103 of the method, thecutting blades 13 cut undergrowth adjacent to a third side 39 (FIG. 9)of the fence post 31 as the planetary gearbox assembly 40 completes itspartial rotation around the fence post 31.

FIG. 11 is a perspective view of an exemplary planetary gearbox assembly40 according to an embodiment of the present disclosure. The pluralityof support arms 46 extends from the top plate 45 of the planetarygearbox assembly 40 and supports the shaft sleeve 50, which is disposedgenerally perpendicularly with respect to the top plate 45. The shaftsleeve 50 connects to the lift frame (not shown) which structurallysupports the weed cutter 10 while allowing the planetary gearboxassembly 40 to rotate freely when acted upon by an outside force, asdiscussed previously.

The shaft sleeve 50 contains threads 88 for receiving a nut (not shown).A swivel fitting (not shown) is installed on the shaft sleeve 50 andsecured by the nut. The swivel fitting comprises bearings and allows theplanetary gearbox assembly 40 to rotate freely as discussed above.

The sleeve 50 is hollow so that it can receive the shaft 6 (FIG. 3) thatconnects the sun gear 11 with the right angle gearbox 41 (FIG. 3), viafitting 52. The shaft 6 thus rotates independently from the sleeve 50.

In this embodiment, a bottom end 51 of the shaft sleeve 50 terminatesabove the top plate 45 of the planetary gearbox assembly 40, i.e., theshaft sleeve does not extend downwardly all the way to the top plate 45.

FIG. 12 is a top plan view of a planetary gearbox assembly 40 accordingto an embodiment of the present disclosure. The sun gear 11 andplanetary gears 8 a-8 c are shown in dashed lines as they are disposedbeneath the top plate 45 of the planetary gearbox assembly 40. In thisembodiment, the gearbox assembly 40 forms a cloverleaf shape when viewedfrom the top, with a plurality of protrusions 33 a-33 c each alternatingwith a plurality of indentations 32 a-32 c.

Although the illustrated embodiment is in a general cloverleaf shapewith three protrusions 33 a-33 c, other configurations of the cutter 10may be employed without departing from the scope of the presentdisclosure. For example, the cutter 10 may have two (2) or four (4)protrusions, wherein each protrusion is associated with a cutting headas described herein.

1. A weed cutter comprising: a rotatable housing rotatably affixed to arear of a tractor and pulled behind the tractor, the housing comprising:a rotating shaft coincident with a central axis, the rotating shaftreceiving rotation from a rear power take-off of the tractor; a sun gearrotating around the central axis, wherein the sun gear receives rotationfrom the rotating shaft; a hollow shaft sleeve spaced-apart from a topplate of the housing by a plurality of support arms such that a bottomend of the shaft sleeve terminates above the top plate of the housing,the shaft received by and rotatable within the sleeve; a plurality ofplanetary gears rotatably connected to the sun gear, wherein theplanetary gears rotate around the sun gear as the sun gear rotates; anedge guard around the perimeter of the housing; at least one cuttingblade associated with each planetary gear and disposed beneath thehousing, wherein each cutting blade rotates when its respectiveplanetary gear rotates, wherein when the edge guard contacts an object,the housing begins to rotate around the object and the cutting bladescut weeds adjacent to the object, and wherein the cutting blades are notextendable into the earth.
 2. The weed cutter of claim 1, wherein theplurality of planetary gears comprises three (3) planetary gears.
 3. Theweed cutter of claim 1, wherein the housing is in the general shape of acloverleaf with a plurality of protrusions alternating with a pluralityof indentations.
 4. The weed cutter of claim 3, wherein each protrusioncorresponds to at least one cutting blade.
 5. A weed cutter comprising:a cloverleaf-shaped housing rotatably affixed to a rear of a tractor andpulled behind the tractor, the housing rotatable around a central axis,the housing comprising a plurality of protrusions alternating with aplurality of indentations, the housing further comprising a top plate; aplurality of rotating cutting blades, each cutting blade disposedbeneath a protrusion; a sun gear rotating around the axis, wherein thesun gear receives rotation from a central shaft coincident with thecentral axis, the central shaft receiving rotation from a rear powertake-off of the tractor; a plurality of planetary gears rotatablyconnected to the sun gear, wherein the planetary gears rotate around thesun gear as the sun gear rotates, and wherein each planetary gear isassociated with a respective cutting blade, a plurality of support armsextending upwardly and angularly from the top plate of the housing, theplurality of support arms terminating at and rigidly affixed to a hollowshaft sleeve that receives the shaft, the hollow shaft sleevesubstantially perpendicular to the top plate, a bottom end of the hollowshaft sleeve terminating above the top plate, such that the shaft sleeveis spaced apart from the top plate; wherein a footprint defined by acutting area of each cutting blade is disposed within a footprint ofeach protrusion, and wherein the cutting blades are not extendable intothe earth.
 6. The weed cutter of claim 5, wherein when one of theplurality of protrusions contacts an object, the housing rotates suchthat the cutting blade beneath the protrusion cuts undergrowth adjacentto the object.
 7. The weed cutter of claim 5, wherein each planetarygear is disposed within one of the protrusions and causes its respectivecutting blade to rotate.
 8. A weed cutter comprising: a housingrotatable about a central axis, the housing rotatably affixed to a rearof a tractor and pulled behind the tractor, the housing comprising afirst protrusion, wherein the first protrusion is associated with afirst cutting head disposed beneath the housing, the first cutting headcomprising at least one cutting blade; a second protrusion, wherein thesecond protrusion is associated with a second cutting head, the secondcutting head comprising at least one cutting blade; an indentationbetween the first protrusion and the second protrusion; a support armassociated with each protrusion, the support arms extending upwardly andangularly from a top plate of the housing, the support arms terminatingat and rigidly affixed to a hollow shaft sleeve that receives a centralrotating shaft, the rotating shaft coincident with the central axis andreceiving rotation from a rear power take-off of the tractor, the hollowshaft sleeve substantially perpendicular to the top plate, a bottom endof the hollow shaft sleeve terminating above the to late such that theshaft sleeve is spaced apart from the top plate; a sun gear rotatingaround the axis, wherein the sun gear receives rotation from the shaft;a plurality of planetary gears rotatably connected to the sun gear,wherein the planetary gears rotate around the sun gear as the sun gearrotates, and wherein each planetary gear is associated with a respectivecutting blade, wherein when the first protrusion contacts an object, thehousing begins to rotate around the object such that the firstprotrusion first contacts the object, then the indentation contacts theobject, and then the second protrusion contacts the object, and whereinthe cutting blades are not extendable into the earth.
 9. The weed cutterof claim 8, wherein each planetary gear causes its associated cuttingblade to rotate.